Process for clamping and tightening diaphragms in filter press type cells for the electrolysis of aqueous hydrochloric acid



8 April 18,1968 P, REWSHAGEN ET AL 3,378,480

PROCESS FOR GLAMPING AND TIGHTENING DIAPHRAGMS IN FILTER PRESS TYPE CELLS FOR THE ELECTROLYSIS OF AQUEOUS HYDROCHLORIC ACID Filed July 29, 1965 PAUL REiNSHAGEN HEINZ SCHMIDT WALDEMAR ZIEMER HEINRICH HENKEL ATTORNEYS United States Patent 0 M 1 Claim. (Cl: 264-453) The present invention relates to a process for clamping and tightening diaphragms in filter press type cells for the electrolysis of aqueous hydrochloric acid.

In the known filter press type cells for the electrolysis of aqueous hydrochloric acid the anode chambers are separated from the cathode chambers by diaphragms made of fabrics that are resistant to chlorine. These fabrics are clamped between the electrode frames by means of elastic packings. The packings simultaneously serve to seal the electrolysis chambers and to fasten the diaphragms along their rims.

According to the latest known embodiment the packing is designed as a frame of soft rubber which is pressed between the electrode frames. The diaphragm is inserted into a slot of the packing and secured by bonding or sewing. One side of each of the frames of the bipolar electrodes is provided with pins serving for the fixation of the packing frame.

The aforesaid kind of fixation and packing, however, has considerable disadvantages.

The soft rubber packing is resistant to chlorine to a limited extent only. There is a danger that the sewn or bonded seams gradually become pervious, so that chlorine and hydrogen may mix with one another. Other packing materials, for example, polytetrafiuoroethylene, cannot be used in the above-described form for technical and economical reasons.

Because of the elasticity of the packing frame it is very difficult and time-consuming to stretch the diaphragm without the formation of creases when fixing it to the packing frame and inserting it into the cell.

The packing frame is a complicated profilated piece which is consequently very expensive and which after a diaphragm has been exchanged can no longer be used. Moreover, it is diflicult to adapt the suspension eyes of the packing frame exactly to the dimensions of, and the distances between, the pins arranged on the electrode frame.

3,378,489 Patented Apr. 16, 1968 Now we have found that the aforesaid disadvantages can be avoided by providing one side of the electrode frame with a groove, placing the diaphragm into this groove and clamping it with a V-ledge, then inserting a packing cord and pressing it against the frame of the neighbouring electrode.

The packing is advantageously made of an appropriate elastic material that is resistant to chemical substances, for example, rubber, impregnated asbestos or asbestos coated with polytetrafiuoroethylene or soft polyvinyl chloride. The packing is used in the form of an endless cord. Its cross-section is of little importance and may be, for example, quadrangular, trapezoidal or round.

The clamping and tightening of the diaphragm according to the invention will now be described in greater detail by way of example only with reference to the accompanying drawing.

Referring to the drawing, an electrode frame 1 is provided on one side with a groove 2 into which a diaphragm 3 is inserted. The diaphragm is fixed by means of a V- ledge 4. If any material of the diaphragm should project at A it is removed. An endless packing 5 is then inserted and pressed firmly against neighbouring electrode 1a. Owing to this operation the packing is pressed against electrode 1 between A and B and against electrode in between C and D and makes the electrode chambers tight to gases and liquids.

When applying the process according to the invention it is no longer ditiicult to insert and clamp in the diaphragm without the formation of creases. The complicated and tedious insertion of the diaphragm into the packing frame and its sewing or bonding can be dispensed with. No pins and eyes are required for fixing the packing, so that the difiiculties which have hitherto been encountered when adjusting the dimensions and distances are also overcome. Moreover, the process according to the invention enables time and expenses to be saved.

We claim:

1. A process for clamping and tightening diaphragms in filter press type cells for the electrolysis of aqueous hydrochloric acid, which comprises inserting the diaphragm into a groove of the electrode frame and clamping it with a V-ledge, then inserting an endless packing cord into the groove and pressing it against the frame of the neighbouring electrode.

References Cited UNITED STATES PATENTS 5/1961 Crean 204-257 XR 8/1967 Isreeli 210-321 

1. A PROCESS FOR CLAMPING AND TIGHTENING DIAPHRAGMS IN FILTER PRESS TYPE CELLS FOR THE ELECTROLYSIS OF AQUEOUS HYDROCHLORIC ACID, WHICH COMPRISES INSERTING THE DIAPHRAGM INTO A GROOVE OF THE ELECTRODE FRAME AND CLAMPING IT WITH A V-LEDGE, THEN INSERTING AN ENDLESS PACKING CORD INTO THE GROOVE AND PRESSING IT AGAINST THE FRAME OF THE NEIGHBORING ELECTRODE. 